Colorimetric response to anions by a robust copper(II) complex of a [9]aneN(3) pendant arm derivative: CN- and I- selective sensing

The 1 : 1 complex [Cu(L)](BF4)(2)center dot MeCN (1) of the tetradentate ligand 1-(2-quinolinylmethyl)-1,4,7-triazacyclononane (L) selectively changes its colour in the presence of CN- in H2O and MeCN (without undergoing decomplexation from the macrocyclic ligand). The same complex in MeCN assumes different colours in the presence of CN- or I.